Implantable medical devices for treating irregular contractions of the heart with electrical stimuli are well known in the art. Some of the most common forms of such implantable devices are defibrillators and pacemakers. Various types of electrical leads for defibrillators and pacemakers have been suggested in the prior art.
A broad group of leads may be characterized by the fact that they are placed transvenously. These leads are introduced into the patient's vasculature at a venous access site and travel through veins to the locations where the leads' electrodes will implant in or otherwise contact coronary tissue. One large subfamily of the group of transvenously-placed leads are those that are implanted in the endocardium (the tissue lining the inside of the heart) of the right atrium or ventricle. Another subfamily that is becoming increasingly used are those leads that are placed in the branch vessels of the coronary venous system.
In general, directing a lead through a patient's vasculature can be a challenging proposition for a cardiac physician. For example, those leads that are placed in a branch vessel of the coronary venous system must be navigated to the right atrium of the heart, into the coronary sinus through the coronary sinus ostium, and then into a desired branch vessel. To assist in such lead placements, a physician will typically use a device such as a guide wire or catheter with a pre-formed bend at its distal end. By rotationally manipulating the proximal end of the device, the distal end of the device can be pointed in a preferred direction, for example, toward a branch entrance. After the device has been placed, a lead will then follow either over the guide wire or within the catheter to the site.
On occasion, a physician might wish to deploy a lead without first navigating another device in advance to the electrode placement site. The flexible nature of leads, though, is such that they exhibit very little “steerability” or distal response to proximal manipulation. One response to this problem is to deploy a lead with a stylet or guide wire (hereafter simply referred to as a stylet) residing in the lead's central lumen to provide shape and steerability to the lead. The stylet would then be removed when lead placement was achieved. Stylets, however, can rotate within the lead lumen. Thus rotation of the stylet does not always impart rotation to the lead. This limits the ability of the physician to rotationally steer the distal end of the lead via proximal manipulation of the stylet.
There is a need in the art for a way of providing torque to the distal end of an implantable lead. There is a further need for providing torque to the distal end of an implantable lead with a stylet.